Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare read-only, idempotent, open-world. Description adds critical behavioral context: the report is paid (0.02 USDC via x402 or 10 API credits) and sourced from RDW open data. It does not mention rate limits or response pagination, but payment and source are valuable additions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core purpose, then a dense list of report fields. The single long sentence packs information efficiently, though it lacks structural breaks. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, so the description compensates by enumerating returned fields (make, model, APK, defects, recalls, odometer verdict, etc.) and stating the language (English), source, and cost. Complete for invoking the tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% for the single parameter, with an example plate. The description only says 'Input: Dutch licence plate', which adds no meaning beyond the schema. Baseline 3.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource (Netherlands licence plate check) and enumerates the full report contents (make, model, APK, etc.), clearly distinguishing it as the detailed paid report. The agent can tell it is a Dutch vehicle history report, not a basic lookup or unrelated tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides a target audience ('used-car buying, fleet, leasing and insurance agents') but does not name the alternative nl_vehicle_basic or state when not to use this paid report. Implied usage only, no explicit routing to siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.